Process for the preparation of macrocyclic lactones

ABSTRACT

Macrocyclic ketones are converted into the corresponding lactones with a peracid in the presence of a boron trifluoride etherate catalyst and an inert solvent to form a reaction mixture. This mixture is heated until the conversion is complete and the desired lactones can be recovered by conventional means. The novel lactone obtained, 1-hydroxy-9-cyclohexadecanolide, is useful as a fragrance ingredient.

United States Patent [191 Mookherjeeet al.

PROCESS FOR THE PREPARATION OF I MACROCYCLIC LACTONES Inventors: Braja D. Mookherjee, Matawan; William I. Taylor, Summit, both of Appl. No.: 156,955

Related US. Application Data Continuation of Ser. No. 18,701, Mar. 11, 1970. abandoned.

"us. Cl ..260/343, 252/522 Int. Cl. ..C07d 9/00 Field of Search. ..260/343 Apr. 17, 1973 [56] References Cited UNITED STATES PATENTS 2,417,151 3/1947 Collaud ..260/343 2,936,310 5/1960 Beets et a1. ..260/343 X 3,584,067 6/ l 971 Story ..260/343 Primary Examiner-John M. Ford Attorney-Lorirner P. Brooks et a].

.[ 5 7 ABSTRACT Macrocyclic ketones are converted into the cor responding lactones with a peracid in the presence of a boron trifluoride etherate catalyst and an inert solvent to form a reaction mixture. Thismixture is heated until the conversion is complete and the desired lactones can be recovered by conventional means. The novel lactone obtained, l-hydroxy-9- cyclohexadecanolide, is useful as a fragrance in gredient.

4 Claims N0 Drawings PROCESS FOR THE PREPARATION OF MACROCYCLIC LACTONES This application is a continuation of application Ser. No. l8,70l,filed Mar. 11, 1970, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to a process for the preparation of macrocyclic lactones. More specifically, the

present invention comprises a process whereby macro- 1O cyclic ketones are treated with a peracid and converted into the corresponding macrocyclic lactones in a reaction wherein boron trifluoride etherate is used as a catalyst.

- The macrocyclic lactones produced by the process of the present invention possess a most desirable type of musk odor and, therefore, have attracted much attention. The odor of musk is perhaps the most universally appreciated fragrance and is usually thought of as the animal note in perfumes.

A number of routes for the production of these macrocyclic lactones from various starting materials are available, but they are rather slow and cumbersome. None of theseprocesses utilize a peracid and boron trifluoride etherate to produce the macrocyclic lactones. Peracetic acid has been used to convert cyclic ketones to the corresponding cyclic lactones, however, the cyclic compounds have been only small-membered rings, see Starcher and Phillips, Am. Soc, 80, 4079 1958). McClure and Williams [J. Org. Chem. 27, page 24 (1961)] disclose the use of a hydrogen peroxideboron trifluoride etherate oxidizing agent for converting simple aliphatic ketones to the corresponding esters, however, this is not applicable to the conversion of macrocyclic ketones to the corresponding macrocyclic lactones.

It is, therefore, an object of the present invention to provide a process for the preparation of macrocyclic lactones.

It is a further object of this invention to provide a' process for converting macrocyclic ketoneswith a peracid in the presence of a boron tribluoride etherate catalyst into the correspondingmacrocyclic lactones.

Other objects of the present invention will be set Y forth in, orbe apparent from, the following detailed description of the invention.

THE INVENTION These objects are achieved by the process of the present invention wherein the starting material is a present conversion of macrocyclic ketones to the corresponding macrocyclic lactones with a peracid is efpresence of an inert solvent. The reaction is carried out by heating the reaction mixture comprised of the macrocyclic ketone, the suitable peracid, the boron tribluoride etherate catalyst and the inert solvent to a temperature of from about 40C. to about C. Preferably, the reaction is carried out at a temperature of about 45C. to about 55C. The reaction can be carried out during a period of about 10 hours to about 16 hours until the reaction is complete. In general,reac' tion times of about 12 .hours are preferred. The reaction is normally carried out at atmospheric pressure; however, should a reaction appear to be sluggish, higher pressures can be used in order to raise the temperature and allow the reaction to proceed.

The general reaction of the present invention is illustrated by the equation below:

BF; etherate (CH2), (CHM peracid solvent EH fin ,CHz): CHM minor products The principal product is the macrocyclic lactone corresponding to the macrocyclic ketone starting material.

The macrocyclic lac tone product can be recovered by conventional means from the reaction mixture of the above general equation. These lactones have a highly desirable and useful odor characterized as a musk odor. They can be utilized as a component of perfume compositions to promote a musk fragrance. Perfume compositions containing from about l.0 percent to about 50.0 percent by weight based on the active fragrance ingredients before dilution are desirable and useful. These macrocyclic lactones can also be utilized as intermediates in the synthesis of other macrocyclic compounds.

As stated above, boron trifluoride etherate is utilized as a catalyst in the present invention. Although boron trifluoride etherate can be classified as a Lewis acid, i.e., a substance which can accept a lone pair of electrons from another substance to complete the election ring system of one of its own atoms, other similar Lewis acid compounds such as aluminum chloride, stannous chloride and zinc chloride have been found not to be useful in the process of this invention. The boron trifluoride etherate is used in catalytic amounts.

As stated above, the macrocyclic ketone, the peracid and the boron trifluoride etherate catalyst are combined in the presence of an inert solvent. Suitable inert solvents include chloroform, ether, methylene chloride and the like. Chloroform is a preferred solvent.

As stated heretofore, the macrocyclic ketone is treated with a peracid such as peracetic acid, perpropionic acid, perbenzoic acid, perphthalic acid and other similar peracids in the presence of the catalyst to form the corresponding macrocyclic lactone. The peracid is utilized in excess and preferably in a molar ratio of peracid to macrocyclic ketone of from about 3:1 to about 6:1, preferably about 4: 1. If a ratio of less than about 3:1 peracid to macrocyclic ketone is used, then poor yields of macrocyclic lactone will result, and if a ratio of greater than 6:1 is utilized, then polymerization problems may result. 7

The following examples will illustrate in detail the manner in which the invention may be practiced. It will be understood, however, that the invention is not confined to the specific limitations set forth in the individual examples, but rather to the scope of the appended claims.

EXAMPLE 1 Preparation of cyclohexadecanolide from cyclohexadecanone An apparatus consisting of a 100 ml. reaction flask equipped with an addition funnel, magnetic stirrer, thermometer and reflux condenser fitted with drying tube is charged with 2.15 g. (0.009 mole) of cyclohexadecanone and 18 ml. of chloroform. 0.45 ml. of freshly distilled 98 percent boron trifluoride etherate is then added over a period of minutes and the temperature rises from 25 to 29C. and the solution assumes an orange color. 5.13 g. (0.027 mole) of 40 percent peracetic acid is then added over a period of minutes and the temperature rises to 33C. and the solution becomes pale yellow. The temperature is then raised to 45C. and the contents are stirred for 11% hours. The solution is then cooled and ml. of water are added and the organic layer is then extracted twice with 50 ml. portions of hexane, washed three times with 50 ml. portions of a saturated sodium chloride solution and dried over anhydrous sodium sulfate. The solvent is then removed in vacuo yielding 2.65 g. of crude material which is then chromatographed to obtain 0.963 g. of cyclohexadecanolide.

EXAMPLE II Preparation of 1-hydroxy-9-cyclohexadecanolide from l-hydroxy-9-cyclohexadecanone An apparatus consisting of a 100 ml. reaction flask fitted with an addition funnel, mechanical stirrer, thermometer, reflux condenser, heating mantle and thermo watch is charged with 2.0 g. (0.0078 mole) of 1- hydroxy-9-cyclohexadecanone, 40 ml. of chloroform and 6.0 g. of boron trifluoride etherate and the mixture is stirred. Over a fifteen minute period, 5.0 g. (0.028 mole) of 40 percent peracetic acid are added and the resulting reaction mixture is then stirred for 12 hours at 50C. i 5C. The chloroform layer is then washed three times with 20 ml. portions of a 50 percent sodium chloride solution and twice with cold water until neutral and then dried over sodium sulfate yielding 2.0 g. of crude material. This crude material is then chromatographed to obtain 0.35 g. (30 percent yield) of lhydroxy-9-cyclohexadecanolide.

When the procedures set forth in Examples 1 and 11 are duplicated using stannous chloride, aluminum chloride and zinc chloride in place of boron trifluoride etherate as the catalyst, no significant yields of lactone are obtained.

EXAMPLE III A perfume composition is prepared by admixing the This perfume composition is found to have a desirable musk fragrance quality.

EXAMPLE IV A total of 100 g. of soap chips is mixed with 1 g. of the perfume composition prepared in Example 111 until a substantially homogeneous composition is obtained. This homogeneous composition is then pressed into a bar having a desirable musk scent.

What is claimed is:

l. The process for the preparation of macrocyclic lactones by conversion of a macrocyclic ketone having the general formula wherein R is a substituent selected from the group consisting of hydrogen, hydroxyl and acetoxy and the sum of x and y is an integer from 10 to 16, which process comprises the successive steps of: (a) combining said macrocyclic ketone with a peracid and a boron trifluoride etherate catalyst in the presence of an inert solvent to form a reaction mixture and (b) heating said reaction mixture to effect the conversion reaction.

2. The process of claim 1, wherein the peracid is used in a molar ratio of peracid to macrocyclic ketone of from about 3:1 to about 6: l.

3. The process of claim 1, wherein the temperature of step (b) is from about 40C. to about C.

4. 1-hydroxy-9-cyclohexadecanolide. 

2. The process of claim 1, wherein the peracid is used in a molar ratio of peracid to macrocyclic ketone of from about 3:1 to about 6:1.
 3. The process of claim 1, wherein the temperature of step (b) is from about 40*C. to about 70*C.
 4. 1-hydroxy-9-cyclohexadecanolide. 